This repo contains my work on reverse-engineering, hacking, modifying and upgrading the Yamaha PSS-270 portable electronic "toy" keyboard.
My goal is to outfit the device with various modern features, including but not limited to:
- MIDI in and out capability, with ability to control all functions of the device
- USB sound output capability (a USB sound device that appears as a "mic" to a PC)
- USB power and Rechargeable Li-Ion battery power
- Onboard MIDI playback (SD card, USB, etc.)
- Direct access to the OPL chip (e.g. use the keyboard as an external OPL synth, playback OPL dumps, etc)
- And more...
This repository will archive documentation and code that I find and write to further this effort.
The Yamaha PSS-270 hardware consists of the following:
- HD6301 main CPU
- 4KB of ROM (unlikely to be able to get a ROM dump, sadly)
- 128 bytes onboard RAM
- 29 GPIO lines
- Actual part number is HD6301YB61P/XC194001. No data on these part numbers, likely the specific mask ROM part numbers for this keyboard
- YM2413 "OPLL" synthesizer chip, based on OPL2 with cost-reducing modifications
- Other ICs in the device according to the schematic:
Main system TTL voltage is 5V. Since input voltage comes from 9V-12V of source power (either from DC input jack or batteries) there is a 5V regulator onboard. We could bypass this regulator for a direct 5V power feed from USB.